Electrical contact assembly for connecting a battery to a circuit

FIELD OF THE INVENTION

0001The present invention relates to an electrical contact assembly. More particularly this invention concerns such an assembly of the type used to connect a removable battery, e.g. in a cell phone, to an electrical circuit, e.g. a printed-circuit board.

BACKGROUND OF THE INVENTION

0002A standard contact assembly has a dielectric mounting block having inner and outer faces and at least one conductive contact unitarily formed of elastically deformable metal. This contact has a center web set in the block, an inner leg extending from the web past the inner face and elastically deflectable toward the inner face and toward the center web, and an outer leg extending from web and elastically deflectable from an outer position spaced well outward of the outer face and spaced from the web to an inner position closely juxtaposed with or even touching the web.

0003Such a contact assembly can be mounted, for example, in a wall of a cell phone, between the openable battery compartment and the interior compartment holding the phone's circuitry. Each inner leg bears on and makes permanent electrical contact with a trace of the printed-circuit board carrying this circuitry. Each outer leg can bear on a terminal of a removable battery, typically of the replaceable and rechargeable type. British patent 833,038 of R. Firman, German patent 3,338,080 of G. Muscaglione, and German patent 198 34 375 of K. Bauer describe typical such contact assemblies. Three contacts are provided normally on one mounting block to allow three electrical connections to be made to the battery.

0004In today's very small electronic equipment, in particular cell phones, it is important that every element be made as compact as possible. The above-described contact assemblies however cannot be reduced beyond a certain thickness, is as otherwise the outer leg at least will not bear with sufficient force against the battery terminals to form a good long-term electrical connection. The stroke of the outer leg must be maximized to ensure that it is deformed considerably in its inner contacting position, and this relatively long stroke takes up valuable space inside the device it is mounted in.

OBJECTS OF THE INVENTION

0005It is therefore an object of the present invention to provide an improved contact assembly.

0006Another object is the provision of such an improved contact assembly which overcomes the above-given disadvantages, that is which is extremely compact, yet which still forms a strong electrical connection.

SUMMARY OF THE INVENTION

0007A contact assembly has a dielectric mounting block having inner and outer faces, and a conductive contact unitarily formed of elastically deformable metal. The contact has a center web set in the block, an inner leg extending from the web past the inner face and elastically deflectable toward the inner face and toward the center web, and an outer leg extending from web and elastically deflectable from an outer position spaced well outward of the outer face and spaced from the web to an inner position extending at least partially inward past the web.

0008The ability of the outer leg to move inward past the web means that it has a substantial stroke and can therefore be built into a thinner mounting block. As a result, it can bear with quite some force on whatever it is connecting to, but still is of very compact dimensions.

0009The contact is further formed with inner and outer U-shaped bights connecting the respective legs to the web. In addition the bock is formed on the outer face with an inwardly directed abutment. The outer leg has a tip bearing outward on the abutment in the outer position. In fact the tip bears with prestress against the abutment so that even when only deflected slightly the outer leg will press with its prestress force on the terminal it is engaging. Unlike a tip which stands free, the outer contact according to the instant invention resists displacement from its outermost starting position with considerable force so that, even if just deflected inward a tiny bit, it will press with this considerable force on the battery terminal or other circuit element it is making an electrical connection with.

0010The web according to the invention is formed with a cutout through which the tip passes on movement of the outer leg from the outer position to the inner position. This cutout can be a laterally open notch, but according to a particular feature of this invention it is formed as a notch wholly bounded by the web, that is a hole. The web is substantially wider at the notch than the tip.

0011The bights in accordance with the invention are at opposite ends of the web and the legs extend oppositely toward each other from the respective bights. This gives the contact an S- or Z-shape. Since the two legs bend in from opposite ends, the web will not tend to cant or twist in the mounting block but instead will sit flatly therein when in use.

BRIEF DESCRIPTION OF THE DRAWING

0012The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

0013<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view of the contact assembly according to the invention;

0014<figref idref="DRAWINGS">FIG. 2</figref> is an edge view of the contact assembly;

0015<figref idref="DRAWINGS">FIG. 3</figref> is a cross section of the contact assembly;

0016<figref idref="DRAWINGS">FIG. 4</figref> is a side view of-the contact assembly;

0017<figref idref="DRAWINGS">FIG. 5</figref> is a perspective view of one of the contacts in the relaxed condition;

0018<figref idref="DRAWINGS">FIG. 6</figref> is a view like <figref idref="DRAWINGS">FIG. 5</figref> but with the outer leg in the inner position; and

0019<figref idref="DRAWINGS">FIG. 7</figref> is a sectional view illustrating the contact assembly in use.

SPECIFIC DESCRIPTION

0020As seen in <figref idref="DRAWINGS">FIGS. 1 through 6</figref>, a contact assembly <b>10</b> according to the invention basically comprises an injection-molded dielectric plastic mounting block <b>11</b> and three identical sheet-metal contacts <b>12</b>, typically made of copper- or gold-plated steel. Here as shown in <figref idref="DRAWINGS">FIG. 7</figref> the mounting block <b>11</b> is adapted to be set in a hole <b>33</b> in a wall <b>32</b> between a compartment holding a battery <b>35</b> and a compartment holding a circuit board <b>34</b>. The contacts <b>12</b> each connect a respective trace <b>34</b><i>a </i>of the circuit board <b>34</b> with a respective terminal <b>35</b><i>a </i>of the battery <b>35</b>.

0021Each contact <b>12</b> basically comprises a planar central web <b>15</b>, an outer leg <b>13</b> connected to one end of the web <b>15</b> via a U-shaped bight <b>20</b>, and an inner leg <b>14</b> connected to the opposite end of the web <b>15</b> by another U-shaped bight <b>28</b>, all unitarily formed with each other from a bent sheet-metal stamping. The web <b>15</b> has a widened portion <b>18</b> that fits tightly in a complementary region <b>19</b> of a notch <b>16</b> of the block <b>11</b>. In fact the widened portion <b>18</b> is such a tight fit that when it is forced in direction <b>17</b> (<figref idref="DRAWINGS">FIG. 3</figref>) into the region <b>19</b>, it solidly locks the contact <b>12</b> in place.

0022The inner leg <b>14</b> is of fairly simple construction and has an inwardly (toward the web <b>15</b>) concave outer end <b>29</b> that rides on the respective trace <b>34</b><i>a</i>. It extends from the end of the web <b>15</b> formed with the widened portion <b>18</b> and when unstressed extends at a small acute angle to the web <b>15</b> as shown in <figref idref="DRAWINGS">FIGS. 2</figref>, <b>3</b>, <b>4</b>, <b>5</b>, and <b>6</b>. When installed as shown in <figref idref="DRAWINGS">FIG. 7</figref> it extends almost parallel to the web <b>16</b> and barely projects past an inner planar face of the block <b>11</b>.

0023The outer leg <b>13</b> extends from the opposite end of the web <b>15</b> and has an inwardly concave contact portion <b>30</b> lying between a body portion <b>21</b> and an inwardly convex tip <b>27</b>. The contact portion <b>30</b> engages the battery terminal <b>35</b>. The tip <b>27</b> is only about one-third as wide as the contact portion <b>30</b> and as the web <b>15</b>. The web <b>15</b> according to the invention is formed with a full-length notch or slot <b>31</b> that is slightly wider than the tip <b>27</b> so that as described below the tip <b>27</b> can pass inward through this slot <b>31</b> when the leg <b>13</b> is pressed inward.

0024The mounting block is formed with an abutment pocket <b>25</b> having an inwardly directed surface <b>26</b> against which an outer face of the outer-leg tip <b>27</b> normally bears with some prestress. Thus as shown in <figref idref="DRAWINGS">FIG. 3</figref> before a battery <b>35</b> is installed the contact portion <b>30</b> projects well past the outer face of the block <b>11</b> and the tip <b>27</b> bears with quite some force on the abutment surface <b>26</b>. When a battery <b>35</b> is installed, the outer leg <b>13</b> moves inward as indicated by arrow <b>36</b> (<figref idref="DRAWINGS">FIGS. 4 and 5</figref>), with the tip <b>27</b> moving away from the surface <b>26</b> and eventually passing through the slot <b>31</b> in the web <b>15</b> as shown in <figref idref="DRAWINGS">FIG. 7</figref>.

0025The prestressing of the tip <b>27</b> against the surface <b>26</b> ensures that even if only deflected inward slightly, the region <b>30</b> will bear with quite some force against the battery terminal <b>35</b><i>a</i>. In addition the ability of the tip <b>27</b> to move inward past the web <b>15</b> means that the arm <b>12</b> can deform through a considerable stroke even through the entire assembly is of relatively modest thickness, measured perpendicular to the web <b>15</b>.